Information systems lecture 5
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Information systems Lecture- 5. IS Management System Development process. Chapter objectives:- Systems Development Life Cycle (SDLC) Development of Structured Methodologies Alternative approaches to developing systems Critical success factors.

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Information systems Lecture- 5

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Information systems lecture 5

Information systemsLecture- 5

IS Management

System Development process


Information systems lecture 5

  • Chapter objectives:-

  • Systems Development Life Cycle (SDLC)

  • Development of Structured Methodologies

  • Alternative approaches to developing systems

  • Critical success factors


Information systems lecture 5

1) Systems Development Life Cycle (SDLC)

Systems development could be seen as the simple process of writing programs to solve the needs of the user. Unfortunately the user knows what he wants but has no technical expertise while the programmer understands the computer but not the user environment.

This communication gap between the customer and the service provider must be handled by an intermediary, the systems analyst.

Broadly speaking therefore the systems analyst translates user’s needs into detailed specifications for implementation by the programmer.


Information systems lecture 5

The number of stages and names to describe those stages differ slightly between

organizations; but the SDLC normally covers the activities shown in the figure, each with a primary purpose.

Systems Development Process


Information systems lecture 5

1.1 Preliminary Investigation

The preliminary investigation is carried out to determine the scope and objectives of the new system and to investigate whether there is a feasible solution.

At this stage an analyst or small project team is authorized to investigate the real potential of the new application. During this brief study the analyst must investigate the problem and the existing system sufficiently to be able to identify the true extent and purpose of the new application.


Information systems lecture 5

  • In order to ensure that the new system would be of greater benefit to the organization than other competing requests for proposals, a feasibility study must be performed covering the following three major areas:

  • Economic feasibility to measure the costs and benefits of the new system.

  • Technical feasibility to ensure that the organization has sufficient hardware, software and personnel resources to develop and support the proposed system.

  • Operational feasibility, the willingness and ability of management, users and

  • Information Systems staff in the organization to build and use the proposed system.

  • The output from this preliminary investigation is a statement of scope and objectives (often termed the project charter) together with a feasibility report. This document is submitted to management where a decision is made as to whether or not the development project should continue.


Information systems lecture 5

  • 1.2 Systems Analysis

  • In this stage the analyst investigates the needs of the user and develops a conceptual solution to the problem. One human failing we all tend to exhibit is to rush into proposing solutions before we fully understand the problem we are trying to solve. It is therefore important for the analyst to develop a broad, conceptual solution to the problem (what needs to be done) prior to launching into the detailed physical design where we specify how the system will work.

  • The analysis phase should include the following discrete steps:

  • Understand how the existing system operates. This information can be obtained by observing people at work, interviewing users, and studying procedure manuals and other supporting documentation, questionnaires and visits to other organizations.

  • Document the current physical system. A major problem in the past was how to record all the detail about the system. Most of it could be found only in the analyst’s head or draft notes. Here the basic tools of structured systems analysis such as the data flow diagram (DFD), the entity relationship diagram (ERD) and data dictionary (DD) can be used to represent graphically and record the data and procedures.


Information systems lecture 5

  • Define the problem areas. These may include such issues as poor response times in the existing system, poor presentation of current information, high costs or weak controls in the current system, waste and sometimes duplication.

  • Identify new requirements. The analyst must attempt to identify new user requirements and look for new and improved procedures that can be incorporated into the system.

  • Identify possible solutions. Having derived objectives for the new system from the previous stage, the analyst now develops a conceptual model of the new system in conjunction with the user. This may involve the investigation of alternative physical designs,

  • The culmination of the analysis stage is the preparation of the formal user requirement specification (URS) that incorporates a logical model of a system that will meet the user’s requirements. A large proportion of the functional description and data specifications is best communicated from the analysis stage to the design stage through the graphic and electronic output from the structured tools used in the analysis process.

  • Again management is required to review the status of the project and to make its go/no-go decision.


Information systems lecture 5

1.3 Systems Design

The analysis stage of the SDLC has clearly identified what must be done in order to meet the user’s requirements.

In the past, most large organizations developed their own applications as no two organizations were exactly alike, and they could afford the investment in systems developed around their user’s needs.

Today the picture is changing as custom-built software is becoming very expensive to develop and even more so to maintain. Computer applications are large, complex and integrated and many businesses have become non competitive because of their inability to develop systems that adequately support their business activities.

On the reverse side, packages (pre-written software applications) are becoming more common and can be customized to meet the needs of each organization. With major benefits in terms of speed of installation, cost, low maintenance and low risk, more and more companies are switching to packaged applications software.


Information systems lecture 5

  • The objective of the design stage is to determine exactly how the new system will work, and to communicate this information in a document referred to as the detailed systems specification.

  • We need to go through the following process when designing computer systems:

  • The technical platform on which the software will run. The new application may need new hardware, operating systems software and network connections.

  • Output reports and enquiry screens.

  • Input forms and data capture procedures.

  • Physical file and database layouts.

  • Description of the workings of each program module.

  • New clerical processes and procedures that will be required to interface with the new system.


Information systems lecture 5

  • There are three main objectives which the designer has to bear in mind while evolving and evaluating a design:

  • Performance. How fast the design will be able to do the user’s work given a particular hardware resource.

  • Control. The extent to which the design is secure against human errors, machine malfunction, or deliberate mischief.

  • Changeability. The ease with which the design allows the system to be changed to, for example, meet the user’s needs to have different transaction types processed.

  • The output from systems design is a detailed design specification incorporating technical, input, output, data and process specifications


Information systems lecture 5

  • 1.4 Systems Build

  • Programming the new system. Poor design will make it difficult for the programmer to construct the system, and it may be inefficient and difficult to maintain.

  • Programmers can code, data base administrators set up the database, hardware suppliers install and test networks and equipment, and we can begin to train the end-users to prepare them for the implementation phase.

  • Programming includes the following steps:

  • Database construction

  • Program coding and testing

  • Systems testing to check the system can handle expected loads and meets physical performance criteria

  • Finalize manual procedures


Information systems lecture 5

  • 1.5 Systems Implementation

  • This entails the transition of the completed system into the operational environment, and includes the following tasks (some of which will already have been started in earlier phases):

  • Installation and testing of any new hardware, systems software and network

  • Infrastructure.

  • Train users and operations staff.

  • Transfer data (data conversion)from the manual or old system to the new database where necessary.

  • Perform acceptance testing. This requires careful planning to ensure all data flows, error procedures, interfaces, controls and manual procedures are tested.

  • Complete project documentation


Information systems lecture 5

  • When the new system has been in operation for a few months, a post implementation audit should be carried out. This audit must ascertain whether the project has achieved the initial objectives specified in terms of:

  • Meeting initial scope and objectives

  • Anticipated costs and benefits to the organization

  • User satisfaction with the new system

  • Performance (response/turnaround time, reliability)

  • Adherence to standards

  • Quality of final product

  • Project performance in terms of cost and time.


Information systems lecture 5

1.6 Maintenance

Finally resources will be required to maintain and enhance the system over its operational life which can vary between 4 and 10 years. This will ensure that there is a defined time when the project is completed and that all the required documentation is produced.

There are many systems in existence that are still supported by the original developer; and all knowledge of the system exists only in that individual’s head. The problem is that when this person leaves, there is no one with any knowledge of the system and the organization is at risk.


Information systems lecture 5

The following table summarizes the important tasks in the six stages of the SDLC and highlights the main deliverables from each task.

SDLC Tasks


Information systems lecture 5

  • 2) Development of Structured Methodologies

  • New and innovative systems development techniques are frequently proposed by researchers and practitioners and, over time, these formal methods have replaced the traditional pragmatic approach to developing computer systems.

  • 2.1 Structured Programming

  • Programs were written in low level languages with little or no support documentation and, over time, the code became almost impossible for maintenance programmers to understand and fix. So arose the need to introduce a set of standard rules and procedures for writing programs, often referred to as structured programming.

  • Some of the key techniques in the structured programming approach include:

  • A limited set of simple control structures (to control branching and looping)

  • Standard naming conventions for data and procedures

  • Self documenting programs.

  • Structured programming techniques ensured that programs were easier to write and test and much easier to maintain


Information systems lecture 5

2.2 Structured Design

IS researchers, and in particular Larry Constantine, studied theproblems of program sizeand complexity, and determined that, as a problem grew in size, so there was a more than proportional growth in the complexity of the problem and therefore in programming time.

He advocated that all systems should be made up of small modules each no longer than fifty lines of program code.

This technique was known as structured design; and a graphical representation of the modules and their relationships known as a structure chart, was developed to assist in the process.


Information systems lecture 5

  • 2.3 Structured Analysis

  • The analysts needed tools and techniques which could be used to define and communicate the user’s requirements to the systems design stage. These structured tools and techniques included:

  • Data Flow Diagrams (DFD). These diagrams are used to show how data flows between the various processes in the system. DFD’s are an excellent communication tool as they are simple enough for users to understand and yet detailed enough to form the basis for the systems design process.

  • Entity Relationship Diagrams (ERD). Entity relationship diagrams identify the major objects about which data is stored and chart their interrelationship. Like most formal techniques, its major value is that it forces the analyst into a structured and detailed investigation of all the data used in the system.

  • Decision Trees and Pseudo-code. These tools enable the analyst to express process logic clearly and unambiguously.

  • Project Dictionary. This tool enables the analyst to capture and catalogue the entire system specification on computer with the obvious advantages in reporting, cross referencing and updating.


Information systems lecture 5

Alternative approaches to developing systems

Over the past 40 years, efforts have been made to improve the quality of new systems and to reduce the time and effort expended in their development. The following section provides an overview of some of the significant tools and techniques developed for this purpose.

3.1 Prototyping

3.2 Joint Application Development (JAD)

3.3 Computer Assisted Software Engineering (CASE)

3.4 Object Oriented Development (OOD)

3.5 Other development tools


Information systems lecture 5

  • 3.1 Prototyping

  • One technique that has been incorporated successfully into the SDLC is prototyping. As the name suggests a prototype is a mock-up or model of a system for review purposes.

  • The two main approaches to the use of prototypes in the SDLC are:

  • Discovery prototyping where the analyst builds a skeleton of the final product in the analysis stage of the project in order that the user may better understand the workings of the final system.

  • Evolutionary prototyping where a working model is built with the intention of later refining it into the operational system.

  • Prototyping can offer IS developers many advantages:

  • Assists in clarifying user’s requirements

  • Improves user communication and commitment

  • Improve the functionality and quality of the user interface

  • Assist in identifying problems earlier in the development life cycle.


Information systems lecture 5

3.2 Joint Application Development (JAD)

One major problem in systems development projects is the lack of real communication, understandingand consensus between users, managementand the development team.

Instead of the traditional one on one interviews spread over weeks and often months, the JAD approach involves a series of highly structured workshops where stakeholders focus on any one of the planning, analysis, design and implementation stages of the life cycle.

One obvious advantage of this approach is a reduction in the time it takes to develop systems


Information systems lecture 5

3.3 Computer Assisted Software Engineering (CASE)

Offering a set of integrated electronic tools for use in the SDLC. During the first phase of system development.

Provide the analyst with computerized tools to complete and document the analysis .

Provide detailed design stages of the development project by graphically modeling the data requirements.

Providethe business process flows that the intended application has to address.

The resultant application model is then used as a blueprint for the actual implementation in computer code. The tools that are geared specifically for this modeling phase are referred to as upper-CASE or U-CASE tools.

Lower-CASE tools specialize in the second phase of system development.

Integrated or I-CASE aims to automate both phases i.e. a combination of upper and lower- CASE tools in one single package.


Information systems lecture 5

  • Most CASE environments use an electronic project dictionary as a repository and can include:

  • Graphic tools for charting diagrams such as DFD’s, ERD’s and Structure charts.

  • 4th generation languages or application generators to assist with prototyping

  • Data dictionary facilities to record and maintain data about data, processes and other system details.

  • Quality control facilities to check specifications and code for correctness.

  • Code generators to reduce programming effort.

  • Spreadsheet models to assist with cost/benefit analysis.

  • Project management tools to plan, monitor and control the development cycle.


Information systems lecture 5

3.4 Object Oriented Development (OOD)

The object oriented approach attempts to build components (objects) that model the behavior of persons, places, things or concepts that exist in the real world and then to build systems from these components.

Not designing and building unique systems for motor cars or televisions; they are mostly built up from a set of common, interchangeable components.


Information systems lecture 5

3.5 Other development tools

Visual programming tools. The power of graphical user interfaces and object-orientation has spawned a number of high-level front-ends or shells to enable non-programmers to generate their own straightforward applications. These visual programming tools allow for the construction of applications by selecting, connecting, copying and arranging programming objects.

Report generators are generally associated with database management systems and allow users to create ad-hoc, customized reports using the data in the database by specifying the various selection criteria and the desired report layout.

Application generators consist of standard building blocks that can be combined or customized to create the required systems. The user specifies the inputs, the output requirements and the various data validations and transformations. Generally, these generators are supported by a comprehensive database management system.

Logic programming for knowledge based systems. Programmers quickly discovered that conventional programming languages were inadequate to develop advanced knowledge based applications, such as expert systems and other artificial intelligence systems.

End-user applications.


Information systems lecture 5

  • Critical success factors

  • Regardless of the development approach that may be used, a number of factors have been identified that are critical to ensuring the success of a systems development project:

  • Well defined system objectives

  • Careful test of feasibility

  • Top management support

  • User involvement to ensure strong commitment

  • Rigorous analysis to ensure detailed, unambiguous user requirements

  • Sound detailed design to ensure an efficient, quality, maintainable system

  • Project management to ensure the development team is managed and controlled.


Information systems lecture 5

DONE!!!

Thank you for listening

  • Any Questions??

  • Please Read Section IV: IS Management of Book(1) Discovering Information systems,Page No. from 134 to 147 for further reading.


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